Phosphine-sulfoxide ligands

The reaction of alcohols with CO was catalyzed by Pd compounds, iodides and/or bromides, and amides (or thioamides). Thus, MeOH was carbonylated in the presence of Pd acetate, NiCl2, tV-methylpyrrolidone, Mel, and Lil to give HOAc. AcOH is prepared by the reaction of MeOH with CO in the presence of a catalyst system comprising a Pd compound, an ionic Br or I compound other than HBr or HI, a sulfone or sulfoxide, and, in some cases, a Ni compound and a phosphine oxide or a phosphinic acid.60 Palladium(II) salts catalyze the carbonylation of methyl iodide in methanol to methyl acetate in the presence of an excess of iodide, even without amine or phosphine co-ligands platinum(II) salts are less effective.61 A novel Pd11 complex (13) is a highly efficient catalyst for the carbonylation of organic alcohols and alkenes to carboxylic acids/esters.62... 

Ruthenium and Rhodium Hydrides Containing Chiral Phosphine or Chiral Sulfoxide Ligands, and Catalytic Asymmetric Hydrogenation... 

This chapter reports principally on studies with ruthenium chiral phosphine and chiral sulfoxide complexes and their use for catalytic hydrogenation. We have used the familiar diop ligand, [2R,3R-(—)-2,3-Oisopropylidene-2,3-dihydroxy-l,4-bis(diphenylphosphino) butane] (7) a related chiral chelating sulfoxide ligand dios, the bis(methyl sulfinyl)butane analog (21) (S,R S,S)-(+)-2-meth-ylbutyl methyl sulfoxide(MBMSO), chiral in the alkyl group and R-(+)-methyl para-tolyl sulfoxide(MPTSO), chiral at sulfur. Preliminary data on some corresponding Rh(I) complexes are presented also. 

Heck reactions are conducted in polar aprotic, cr-donor-type solvents such as acetonitrile, dimethyl sulfoxide, or dimethylacetamide. Reaction temperatures and times largely depend on the nature of the organic halide to be activated and on the catalyst s stability limit. lodo derivatives are much more reactive (<100 °C), so auxiliary (phosphine) ligands are not necessary here. Polar solvents such as DMF, DMAc, and A-methylpyrrolidone (NMP) in combination with NaOAc as base are specifically beneficial in all cases, and even mild phase-transfer conditions in a solid/solution system employing Pd(OAc)2 without phosphine co-ligands), [N(n-C4H9)4]X in DMF (X = Cl, Br), and K2CO3 as base ( Jeffery conditions ) [17, 18]. 

Fig. 21. Triorganotin halides containing an intramolecular coordinating phosphine, phosphine oxide, carbonyl, or sulfoxide ligand.

The reaction described by Eq. 5.8, in which the chloride ligands of [PtCl2(PhCN)2l are replaced while the benzonitrile ligands are unaffected, may be contrasted with the more common mode of reactivity for this complex in which the labile benzonitrile ligands undergo fadle substitution, not only by neutral ligands such as tertiary phosphines, sulfoxides, etc., but also by anions, such as the chloride ion,33 Eq. 5.9 ... 

Henbest and Mitchell [78] have shown that water can be used as hydrogen source with chloroiridic acid (6) as the catalyst through oxidation of phosphorous acid (59) to phosphoric acid (60) in aqueous 2-propanol. Under these conditions, no hydrogen transfer occurs from 2-propanol. However, iridium complexes with sulfoxide or phosphine ligands show the usual transfer from 2-pro-panol [79-81]. 

Several reports have appeared on the effect of additives on the Pauson-Khand reaction employing an alkyne-Co2(CO)6 complex. For example, addition of phosphine oxide improves the yields of cyclopentenones 119], while addition of dimethyl sulfoxide accelerates the reaction considerably [20]. Furthermore, it has been reported that the Pauson-Khand reaction proceeds even at room temperature when a tertiary amine M-oxide, such as trimethylamine M-oxide or N-methylmorpholine M-oxide, is added to the alkyne-Co2(CO)6 complex in the presence of alkenes [21]. These results suggest that in the Pauson-Khand reaction generation of coordinatively unsaturated cobalt species by the attack of oxides on the carbonyl ligand of the alkyne-Co2(CO)6 complex [22] is the key step. With this knowledge in mind, we examined further the effect of various other additives on the reaction to obtain information on the mechanism of this rearrangement. 

The use of chiral tertiary phosphine ligands has been studied most widely, but other chiral ligands such as carboxylic acids (15), imines (8,16), amides (17), amines (18), alkoxides (19), and hydroxammates (13) have been investigated, and we reported recently on some sulfoxide systems (29, 21). 

Amine A-oxides, phosphine oxides and other phosphoryl compounds and analogous arsenic derivatives, and sulfoxides all give well-defined complexes with scandium. In many cases, authors deal with several of these classes of ligand in the same paper, so it will be most convenient to consider them together here. 

Acoustic emission diazine metal complexes, 80 Acrylonitrile metal complexes, 263 Actinide complexes cupferron, 510 dimethyl sulfoxide IR spectra, 490 phosphines SHAB theory, 1040 phthalocyanines, 864 thiocyanates, 236 Actins, 973 Acylates H3-ligands... 

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